Detached Garage - Raising Ceiling Rafters?

[alecmcmahon]

I've read it can be done, but never really branched on to how exactly.

I have a 20x24 foot 2 car detached garage along with the house i just bought.

In the process of gutting out the garage and re-doing it, My hobby is offroading, and with my lifted jeep, it just barely makes it through the garage door.

I'd like to lift the ceiling rafters as high as possible to make room maybe for a lift ( max jax looks great )

There are only THREE ( 3 ) ceiling rafters in the garage currently, looks like it was just used for storage, the ends have just have a nail in each side into the top beam of the wall on each side.

If possible, how would i go about raising these to the safe max. height?


Also, i dont mind relocating two of them like 12" off each end, if i do this, will it pretty much still be the same, and then perhaps do 2 or 3 rafters high up in the ceiling ( whatever max height may be? )

Below are some pictures of what i have.

 

[BetterDays]

Subscribing, as I am wondering too...

Would like to raise mine, as the height of the top of the rafter is just less than 8'.

 

[Phil S.]

Pretty simple process actually. I'm assuming that you are actually talking about the "Rafter Ties" and not the actual rafters. If you want to e-mail me I will explain [email protected]

 

[BetterDays]

Pretty simple process actually. I'm assuming that you are actually talking about the "Rafter Ties" and not the actual rafters. If you want to e-mail me I will explain [email protected]

Can you explain here?

Thanks,
Kevin

 

[Phil S.]

It would be difficult to explain it on this medium since I would have to draw plans (on CAD) and perhaps a telephone converstion or two, plus I would expect compenstion for my time ( $100.00)

 

[alecmcmahon]

Im talking about the Ceiling rafters that go from wall to wall.

And im sure you are very knowledgeable concerning the processes, but I wont be paying anybody any amount of money for some modification tips.

Message board communities on the web are for sharing advice, tips, questions, etc. And not trying to bait somebody in to make a buck for answering a few questions.

Thank you.


But back on topic, from what i understand, the ceiling rafters are holding the walls from bowing under weight correct?

Would i be able to re-locate a rafter on each end, a foot or so out. Then a bunch a bit higher up? And maybe brace the higher ones on top downward on an angle again connecting to each wall in the middle?

 

[mikeyr]

It would be difficult to explain it on this medium since I would have to draw plans (on CAD) and perhaps a telephone converstion or two, plus I would expect compenstion for my time ( $100.00)

Ah...advertising for work! I thought we could not do that here...tell us all or don't advertise.

 

[mikeyr]

When I moved mine up, I was told I go up 1/3rd's of the way up safely by the architect. My contractor went up 2/3rd's and said that is fine.

So for simple math top of the wall is 8' height of peak is 11' which is 3' total difference, you can move them up 1foot from the wall and still have enough strength to hold the wall. My architect/engineer said that 1/3rd is a no brainer, completely safe, my contractor said he was wrong and went up to use the same math 2', his reasoning was that I am reinforcing the end walls with metal simpson strong walls for seismic reasons (the city required it as I was expanding the garage) and those steel walls will hold everything in place. Oh we also doubled up all the ties, there is now a tie every 16" instead of just 3 that were there before.

City inspector did not say anything and signed off on it...so I have to assume its ok, yeah yeah, i know all about inspectors that no nothing about their job but I have to assume my taxes paid for a guy that knew something or I would be mad about my taxes being wasted.

 

[LIVELY]

another thing to do BEFORE you connect the new rafter ties is try to make each rafter as straight as possible[most of the time a couple 2x4's nailed together as a post and a floor jack will do wonders] then nail each cross brace in place[leveled]

same with the ridge pole beam
it takes a little extra time but well worth the effort
good luck --LIVELY

 

[John McA]

Your results may vary - but this is likely worth a little more than $100. Especially if others use this solution:

I have utilized built up horizontal 'beams' at plate height, where the rafters meet the walls. A structural valance. This is (of course) engineered to take the outward load of the roof and, prevent the bowing of the walls. There are other solutions but, this will allow more headroom, works for both gable and hip roofing..

As an Architect, the contractors do say I'm wrong. Lots of contractors. Even those that don't have licenses. Contractors also say concrete cracks in California; plans are only for getting a permit so its cheaper not to; this work doesn't need one; let me have Juan demo that now; I gotta make a supply run (Home Depot and the bank); You let Juan borrowed your ladder, and then he fell? Sure, that Chinese drywall cost the same, honest. We did it that way on the last job so, its ok. Hey, those aren't nail pops, thems picture hooks!

Good luck. Happy memorial day!
John McA

 

[Steve in Mi]

Alec, do you think that Mike's snow load in Santa Barbara, CA. is about the same as yours up there at the Artic Circle? Or where ever you are at.

 

[portcity]

you could construct a scissor trusses to give a little height and a vaulted ceiling, or do as others advised and raise the joist a bit. A 2x6 rafter 16" on center carring roofing & drywall load(20psf live load, 10psf dead load, L240) can span 14'4". So measure up along the rafter that far and thats where your safe stopping distance is. You can determine the height there. If you have different specs, let me know and I can give you the spans or scan the load chart on here for you.

 

[kbs2244]

We have talked about the options for this need a lot.
Do a search.
Moving the cross ties up to the 1/3 point will be allowed in most locations.

But the method I prefer for a long time fix is to jack the whole building up 2 feet and add a knee wall all around.
You get a higher door thrown in.

 

[tcianci]

The framing members that are being refered to as rafter ties or ceiling rafters actually have 2 different names: A "tie" installed at the level of the top plate is actually a ceiling joist, a "tie" installed horizontally a but higher than the plane of the top plate is a collar tie. Although a ceiling joist, which you appear to have 3 of in your structure does keep the walls from spreading, many framers install collar ties about a third to two thirds of the way horizontally from rafter to rafter. Your roof pitch appears rather shallow and the structure would benefit most from the collar ties being installed as low as possible, but you most likely wouldnt have an issue if you were to install collar ties at each bay placed at the lowest possible height that works for how you intend to utilize the garage.

 

[John McA]

We have talked about the options for this need a lot.
Do a search.
Moving the cross ties up to the 1/3 point will be allowed in most locations.

But the method I prefer for a long time fix is to jack the whole building up 2 feet and add a knee wall all around.
You get a higher door thrown in.

Winner: This would also help with roofing longevity, if carefully raised. Taking too much sag out of the roof while adding ties, etc. can shorten roof life - the sheathing can take out the paper and cause it to fail and lead to leaks. BTDT.

 

[Hank McMauser]

from the looks of your pic's and the description, all those are doing(barely so I might add if onle nailed in one plkace at each end)are preventing the walls from spreading as gravity and time tend to work on the rafters, I woiuld think that adding higher placed collar ties every other rafter & properly attaching at each end of the ties would greatly increase the structural integfrity of that roof. As also noted by someone else it may help also to look at the center ridge board and to see if it has sagged over time if it has you could jack it back up prior to installing the collar ties. once the new ties are in, carefully remove the old ties/ceiling joists and your done.

 

[Will S.]

Not a structural engineer, but I'm thinking that attaching collar ties one third the way up the roof rafters on one side, and two-thirds the way up on the opposite side. Then add another set intalled exactly the reverse, on every rafter; collar ties forming an X. Fasten them at the center where they cross (the X).

So it is two collar ties per roof rafter. Your new clearance height is at the highest point in the center, where you need it most.

Any structural engineer types here... is there a problem in doing this?

 

[ebstein]

so, how'd it go???

 

[ozyborn]

Have good footings? Thought of raising the entire thing and putting in a couple rows of cement block? I used cribbing and railroad ties.

 

[06Z06]

Keep us updated !

Jeff C
06 Z
67 Chevelle L-79

 

[Falcon67]

Must have missed this thread a while back.

From what I have learned -

Collar ties do little more than prevent some rafter spread, but the UBC2006 asks for them every 4'. They cannot be more than 1/3 down the rafters from the ridge

Rafter ties - DO NOT install these unless you plan to sister every rafter or upsize the rafters. At more than 1/3 up, they put a tremendous load on the rafter seats that will strain your fastening system and put a spreading load on the walls. None of that is good. When you move up over 1/3 of the rafter you start deducting from the rafter span in increasing amounts. What worked as a 2x6 quickly becomes a 2x8 or 2x10.

After all that - I would put in new 2x8 or 2x10 joists every 4' and sister the existing joists with new wood, then glue and screw the new to the old. I'd then install rafter/plate hurricane ties and maybe even angle brackets from each end of a joist to a stud. I'd then jack the entire building up 12", knock off the bottom plates, sister in 9' studs and new plates, then drop it back down on the foundation.

LOL - yet another garage on here that looks like the old one I saved. Deja Vu all over again.